1. Field of the Invention
This invention relates generally to communication systems and, more particularly, to assigning uplink and/or downlink capacities in communication systems.
2. Description of the Related Art
Parties in a conventional communication system typically exchange signals over a channel that is divided into an uplink channel and a downlink channel. One example of a conventional wired communication system is a Digital Subscriber Line (DSL). A DSL system, such as Asymmetric DSL, provides high-speed data connectivity over a local loop or a final mile of the communication network. The DSL connection includes an uplink and a downlink channel. Subscribers to the DSL system contract for a selected uplink capacity and a selected downlink capacity. For example, a subscriber to the DSL system may contract for an uplink capacity of 1 Mbps and a downlink capacity of 8 Mbps.
Conventional wireless communication systems include one or more access points, which may also be referred to as base stations or node-Bs, for providing wireless connectivity to one or more access terminals, which may also be referred to using terms such as user equipment, subscriber equipment, and mobile units. Exemplary access terminals include cellular telephones, personal data assistants, smart phones, text messaging devices, laptop computers, desktop computers, and the like. Each access point may provide wireless connectivity to one or more access terminals, such as the access terminals in a geographical area, or cell, associated with the access point. For example, an access point may provide wireless connectivity to access terminals located in a “hot spot” according to an IEEE 802.11 protocol, such as a WiFi protocol. Alternatively, the access point may provide wireless connectivity to access terminals located in the hot spot according to an IEEE 802.16 protocol, a Bluetooth protocol, and or other protocols.
In operation, an access terminal maintains a wireless communication link, or leg, with an access point. The wireless communication link typically includes an uplink for transmitting information from the access terminal to the access point and a downlink for transmitting information from the access point to the access terminal. The downlink may also be referred to as a forward link and the uplink may be referred to as a reverse link. The capacity of the wireless communication link is typically shared by the uplink and the downlink between the access terminal and the access point, as well as by uplinks and/or downlinks associated with other access terminals. Thus, the capacity of the wireless communication link is often a scarce resource. Portions of the available uplink capacity and/or the downlink capacity may therefore be assigned to the wireless communication link between the access terminal and the access point. For example, a capacity of 10 Gbps may be assigned to the uplink and a capacity of 10 Gbps may be assigned to the downlink.
The wired and/or wireless communication systems use a variety of techniques to enforce the agreed-upon capacity limits for the uplink and/or the downlink. For example, a DSL system may simply drop transmissions in excess of the contracted uplink and/or downlink capacities. For another example, if an access point in a wireless communication system receives information that would need to be transmitted at a capacity of more than the contracted downlink capacity to the access terminal on the downlink, the access point may only transmit information to the access terminal at or below the contracted downlink capacity and choose to ignore, or drop, surplus traffic in excess of the agreed-upon downlink capacity limit. For yet another example, if an access terminal attempts to transmit more than the contracted uplink capacity to the access point on the uplink, the access point may choose to ignore, or drop, surplus traffic in excess of the agreed-upon uplink capacity limit. Dropping surplus traffic is sometimes referred to as “traffic policing.”
Policing traffic based on the separate uplink and downlink capacity limits may reduce the efficiency of wired and/or wireless communication links. For example, conventional traffic policing techniques cannot adaptively change the uplink and/or downlink capacity limits. Accordingly, if a first party in the network is transmitting information to a second party over the downlink at more than the agreed-upon downlink capacity and the second party is transmitting information to the first party over the uplink at much less than the agreed-upon uplink capacity, the conventional traffic policing technique may drop surplus downlink traffic, even though capacity associated with the uplink may be available. Furthermore, even if the uplink and downlink capacity limits could be determined adaptively, variations in the demand for uplink and/or downlink capacity over time could cause a mismatch between the demand for uplink and/or downlink capacity, as well as the allocated ratio of uplink-to-downlink capacity. Responsibility for policing the uplink or downlink traffic in conventional traffic policing schemes rests with the community of users affected by the surplus traffic, and not the device that transmits the surplus traffic.